The present invention relates to a technology for providing means for assigning a specific identification number to an electronic device.
Assignment of a specific number to an electronic device itself such as a semiconductor chip and the like has been examined in view of manufacturing process management (to record information on when it is manufactured, which wafer or chip it is, and the like). Recently, taking application to IC money, IC tags, ID cards, and the like into consideration, it has been recognized that assignment of a specific number unchangeable from outside to a chip itself is an important key and essential to problem solution. In other words, it is important to provide an artificially unforgeable semiconductor chip. Also, such a method for assigning a specific number to a chip or the like which is simple as far as possible is desired in view of cost reduction.
Under the circumstances, a conventional method has been employed in which a fuse element or a programmable element such as an EEPROM (electrically erasable programmable read-only memory) is provided in a semiconductor chip composing a semiconductor integrated circuit and specific identification information is assigned to the programmable element.
Other novel methods have been proposed such as a method that utilizes a flip flop rise pattern formed due to ununiformity in transistor characteristic which is yield by process variation (see, for example, International Publication No. 02/45139). In detail, a plurality of identification elements having the same aspect are formed in the course of a manufacturing process of a semiconductor integrated circuit device and identification information specific to the semiconductor integrated circuit device or a semiconductor chip is set based on a magnitude relationship in physical quantity of the plurality of identification elements which corresponds to the process variation.